An established practice in the building art, particularly where rapid building techniques are concerned, is to apply rain screen cladding to a building construction whose exterior is built up from concrete, blocks, or bricks whose external surfaces are then covered with a weatherproof membrane in which openings are made only where for example windows and doors are to be provided. The rain screen cladding in its simplest form is built up from an array of panels disposed over the surface of the building structure. The panels serve to enhance the appearance of the building and also to partially protect it from direct weathering. In one form the panels may be metal painted, stove lacquered or provided with a plastics coating which can give to the panels a desired colour or decoration appropriate to the desired exterior appearance of the building, and provide protection against atmospheric oxidation of the panels. On other occasions, it has become a practice for decorative facing material to be attached by means of a mounting system bolted or screwed to the rear surface of the panels. Such facing material may be made of stone, as with a granite facing, or of wood.
In one such cladding system the panels are attached to the exterior of the building by fixing to vertical rails disposed at regular intervals around the exterior of the building and generally extending to the height of the building. The rails are generally of angle or U-section and the panels are bent over at their vertical edges to form flanges which enter the interior of the rails. The panels generally are hooked onto transverse member straddling the U-shaped members through the provision of cut-outs on the flanges. Arrangements of such type are described in for example DE-A1-3527224, EP-A-144926 and EP-A-180837.
Whilst such assembly method is relatively quick, it gives rise to practical difficulties. Because of the underlying material and manufacturing tolerance and because the panels may not be rigidly held in position, there is scope for movement up and down and backwards and forwards of the panels, as well as some flexing of the metal thereof and these can, taken together, lead to a lack of security and considerable noise problem especially under windy conditions. Hitherto the problem has been overcome by clamping screwing, bolting or wedging the panels to the vertical rails at a sufficient number of points. This is a time consuming operation to carry out after the panels are in place.
Improvements in respect of these problems are achieved with the facade mounting arrangement of CH-A-639454. Here, the panels are mounted on bolts extending between cut-outs of adjacent flanges. These bolts have parallel flat faces which are introduced along undersize passages into a full width part of the cut-outs in the flanges where they are rotated to extend the width of the cut-out and be retained therein through being too wide to fall into the narrower undersized passage from which they have emerged. The bolts are secured against turning by means of a spring clip. This is however a cumbersome means of holding the panels and still leads to their having some freedom of movement and thus major capability of generating noise.